by Eric Frankowski | Daily Times-Call | June 11, 1999
BOULDER COUNTY -Chewing contentedly on the diffuse knapweed in a small temporary enclosure, the herd of several dozen Cashmere goats had little idea they were the center of attention in a debate over the control of noxious weeds.
Surrounded by a lightweight, portable electric fence, they simply went about their business of mowing the knapweed down to the ground.
But to the handful of journalists, anti-chemical activists and weed experts looking on nearby, their activity was a clear demonstration of just how effective bio-control of the weeds can be.
Lani Lamming, the goats’ owner and a weed scientist with a master’s degree from Colorado State University, put the herd in the field on the county’s Carlson/Lastoka Open Space property southwest of Superior on Wednesday afternoon.
In four hours, the animals sheared off nearly every stalk of the bi-ennial knapweed, leaving the alien weed infestation growing unchecked on the other side of the fence in stark green contrast to the freshly exposed mat of native grass inside the enclosure.
“They love weeds,” Lamming said of her herd, “especially noxious weeds. And they eat it at all stages. It doesn’t matter what time of year.”
The goats were just one of the demonstrations on display at a Sierra Club-sponsored seminar on non-chemical weed management held Thursday.
The point of the workshop, said University of Colorado biology professor Tim Seastedt, was to show there are alternatives to using herbicides for weed control.
By combining tools such as grazing with mowing, hand-pulling, and the use of insects adapted to feed on specific weeds, Seastedt said the spread of noxious weeds can be controlled.
“From a non-chemical standpoint,” he said, “a combination of bio-controls will increase the competitive advantage of native plant species.”
Since 1997, Seastedt has been conducting research on a 160-acre plot on the Carlson/Lastoka property to test the effectiveness of insects on knapweed.
He has introduced five non-native insects onto the property, two that feed on knapweed’s roots, two on its seeds and another that attacks its stem.
The insects, he said, co-evolved with knapweed in Asia and have adapted to feed on it despite bitter chemical compounds that make it unpalatable to native insects.
So far, said Seastedt, the results have been good.
During the workshop, he became elated upon discovering that a weevil species – of which he had introduced only 50 individuals -had spread to the middle of his plot.
“wok,” he said, pointing to fat, cream-colored larvae snuggled fatly into a chamber it had nibbled in knapweed plant’s root. “It’s very optimistic that we were able to find these guys.”
According to Jerry Cochran, the bio-control coordinator with the state Department of Agriculture’s Division of Plant Industry, the bug species has been very effective in knocking back the knapweed at a test site near Chatfield Reservoir south-west of Denver.
The insects “appear to have really opened the plant up to outside stresses,” said Cochran.
During a dry spell in 1995, he said knapweed densities “plummeted” on the site, while those in a nearby field where insects were not present continued to thrive.
According to Seastedt, the alien insects can thrive on knapweed and its bitter taste while native insects cannot because the alien insects co-evolved with it in Asia.
According to Lamming, her goats love the weed for the same reason.
She currently has 550 of the eating machines and recently was awarded a $50,000 contract to control weeds for the Denver Parks, Recreation and Open Space Department along the Cherry Creek and South Platte River corridors.
She has worked with federal, state, municipal and county governments, as well as private landowners, to control weed infestations in Utah, Wyoming and Colorado.
Depending on the specifics of the situation, she charges roughly $100 per acre for her services. And knapweed is not the only noxious plant her goats are good at knocking down.
With 90 percent of their diet consisting of browse -instead of grasses -she said they are also excellent at keeping invaders such as toadflax, thistle and even Russian olives at bay.
Unlike mowing or herbicide use, said Lamming, “the goats are very selective” and do not affect native plants.
Although she said chemicals such as Tordon, which is used in Boulder County for knapweed control, have their place, Lamming said their use must be considered in the context of what owners want for their land.
Boulder County is currently considering the purchase of 10 goats to release on some of its open space properties, but it has not yet done so made the purchase.
County Parks and Open Space officials did not attend Thursday’s demonstration.